<?php
/*
* This file is part of Big Picture Gallery (BPG).
*
* Big Picture Gallery (BPG) is free software: you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation, either version 3 of the License, or
* (at your option) any later version.
*
* Big Picture Gallery (BPG) is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with Big Picture Gallery (BPG).  If not, see <http://www.gnu.org/licenses/>.
*/

class Session {

  const SESSION_STARTED = true;
  const SESSION_NOT_STARTED = false;

  private $sessionState = self::SESSION_NOT_STARTED;

  private static $instance;

  private function __construct() {}

  public static function getInstance() {
    if (!isset(self::$instance)) {
      self::$instance = new self;
    }
    self::$instance->startSession();
    return self::$instance;
  }

  public function startSession() {
    if ($this->sessionState == self::SESSION_NOT_STARTED) {
      $this->sessionState = session_start();
    }
    return $this->sessionState;
  }

  public function __set($name, $value) {
    $_SESSION[$name] = $value;
  }

  public function __get($name) {
    if (isset($_SESSION[$name])) {
      return $_SESSION[$name];
    }
  }

  public function __isset($name) {
    return isset($_SESSION[$name]);
  }

  public function __unset($name) {
    unset($_SESSION[$name]);
  }

  public function destroy() {
    if ($this->sessionState == self::SESSION_STARTED) {
      $this->sessionState = !session_destroy();
      unset($_SESSION);

      return !$this->sessionState;
    }

    return false;
  }
}
?>